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Re: Why can't CSE recognize const_int's in HIGH LO_SUM pair?
- To: rth at redhat dot com (Richard Henderson)
- Subject: Re: Why can't CSE recognize const_int's in HIGH LO_SUM pair?
- From: "John David Anglin" <dave at hiauly1 dot hia dot nrc dot ca>
- Date: Fri, 7 Sep 2001 21:30:05 -0400 (EDT)
- Cc: gcc at gcc dot gnu dot org
> Better would be to emit the actual constants that the insns
> in question will load into the hardware registers.
Jeff probably could give the best answer but I think it has to do with
the way move insns are done in general. I think the philosophy was to
make the rtl match as closely as possible the machine code. However, I recall
a few months ago there were issues with high/lo_sum in pic code generation
and one of the solutions discussed was delaying the generation of high/lo_sum
pairs until after reload. Clearly, it is easier for the compiler to
deal with a simple constant or address.
Dave
--
J. David Anglin dave.anglin@nrc.ca
National Research Council of Canada (613) 990-0752 (FAX: 952-6605)